Linda Greenhouse and Reva Siegel "say one of the things that really politicized the abortion issue was the efforts of those working to re-elect President Richard Nixon in 1972."

"His aides, including future Republican presidential candidate Patrick Buchanan, wanted to lure Northern Catholic voters, who had traditionally voted Democratic, over to the Republican Party."

Nixon "was strongly advised by his strategists ... to make a play for a Northern urban Catholic Democratic vote," says Greenhouse. "A kind of Northern strategy that mirrored the Southern strategy."

In fact, up until then, top Republicans tended to be more in favor of abortion rights than Democrats, including, for much of his first term, Nixon himself....

So, taking his aides' advice, Nixon switched sides on abortion, even reversing an earlier relaxation of an abortion ban in military facilities.